1. Field of the Invention
The present invention relates to medical X-ray imaging, and more particularly the present invention relates to an X-ray system that includes a camera to provide visual feedback to an operator of the system during pre-examination testing and adjustment, including a snapshot of a collimator-shaped patient FOV. In an embodiment, a camera image is provided by the camera to the X-ray system, and a feedback signal is generated in response to the camera image to support collimator and/or X-ray tube adjustment, patient positioning and movement, etc.
2. Description of the Related Art
X-ray imaging systems for digital radiography are used for conventional imaging of anatomical background including solid structures, soft tissue such as in cardiac vascular imaging using such techniques including without limitation digital spot imaging, digital subtraction angiography (DSA) and live fluoroscopy roadmapping. X-ray imaging systems include an X-ray source and X-ray capture device such as image intensifying screen, or digital flat panel detector to convert the X-ray energy defining the radiation image into light. X-ray systems also include various mechanisms for preventing direct exposure from the X-ray beam, scattered X-rays from reaching the detector or image intensifier and other beam-shaping mechanisms including X-ray collimators or beam-limiting devices. X-ray collimators adjust the X-ray beam to an extent necessary for imaging patient anatomy within desired fields of view (FOV). For example, a collimator may be adjusted during the examination for each image taken to optimally cover the part of the image in which no body part, or non-relevant body parts are located, i.e., outside the FOV.
X-ray imaging systems may include various displays, panels, consoles, workstations, etc., with user interfaces such as keyboards, switches, dials, trackballs, joysticks, etc., that enable an operator to view an image and make adjustments for further imaging. Input devices control operations such as the image contrast, brightness, image blur and noise in the produced image. For that matter, because manually setting the collimator parameters, such as at each station in an angiographic study of leg vasculature for a mask run, and saving the settings is cumbersome and time consuming, automatic collimator adjustment functions have been developed. U.S. Pat. No. 6,055,295, commonly owned, discloses a system and method for automatically setting the collimator of an X-ray imaging system at the time of image acquisition.
U.S. Pat. No. 6,106,152, commonly owned, discloses an X-ray imaging system with an X-ray source, X-ray tube and collimator to limit, adjust or shape the radiated X-ray beam. During operation, a test exposure is acquired with the disclosed system and used to adjust the collimator to position the X-ray beam in relation to a digital detector, such as a flat panel detector, focusing the patient FOV. In this way, images may be acquired and processed for desired views. The image processing typically includes adjusting contrast and background removal for desirable imaging quality. But collimator adjusting or adjusting proper distances between the patient and X-ray source may be insufficient nevertheless where the patient or table has moved after set-up. This is particularly so with spot imaging, and techniques where a patient is physically adjusted, and the system parameters physically adjusted, and there is a time lag before the intended examination procedure. Required readjustment of a patient who has moved between system physical adjustment and diagnostic or interventional imaging causes double work, in which the clinician is required to reposition the patient, and possibly recalibrate. Patient movement may be acute where a patient is unconscious, for example, during an emergency intervention, and may move involuntarily.
Where readjustment is required after setup and test imaging, the patient, and possibly the clinician are exposed to unnecessary radiation where the test imaging must be repeated, or the examination is inadvertently conducted with an improper FOV. Again there is a cost in patient throughput time, clinician time and energy, and cost. In addition, where a clinician may wish an alternative X-ray image based on a first image, or a series of images of a fixed patient FOV, repositioning is complicated if the patient has moved without the clinician realizing it until the “next” image is viewed.
It would be well-received, therefore, to the skilled artisan and clinicians alike, to have use of a system and method that overcomes the shortcomings of the prior art, that allows the clinician to be readily sure that the FOV is as arranged prior to test imaging and diagnostic imaging, particularly in cases where the imaging position is modified for particular studies.